A real variety with boundary and its global parameterization

An algebraic variety in R³ is studied that plays an important role in the investigation of the normalized Ricci flow on generalized Wallach spaces related to invariant Einstein metrics. A procedure for obtaining a global parametric representation of this variety is described, which is based on the use of the intersection of this variety with the discriminant set of an auxiliary cubic polynomial as the axis of parameterization. For this purpose, elimination theory and computer algebra are used. Three different parameterization of the variety are obtained; each of them is valid for certain noncritical values of one of the parameters.     

Automated modeling for structural analysis

The numerical computations required for structural analysis are well defined and easy to automate. If structural analysis is to be automated fully, however, the modeling process, as well as the numerical computations, must be automated. This paper outlines a procedure for the automation of the entire modeling and analysis sequence.Structural analysis is considered as one of several planning, design, and analysis applications to be included in a computerintegrated design system. An essential ingredient of such a system is a central data base that supports all applications. A data base using a hierarchicalcomponent-connection concept is first described. A procedure is then outlined by which a modeler program can extract analysis models from this data base. Whereas the central data base describes the structure in terms of its components and connections, the analysis model is in terms of nodes, elements, substructures, slaving constraints, and so on. The features required in a structural analysis program to analyze the resulting model are also described. This program follows well-established principles, but is substantially different in its arhitecture from conventional analysis programs.A simple frame building is used as an example. However, the procedure is believed to be applicable to structures of a variety of types.     

Efficient reanalysis for topological optimization

An efficient reanalysis method for the topological optimization of structures is presented. The method is based on combining the computed terms of a series expansion, used as high quality basis vectors, and coefficients of a reduced basis expression. The advantage is that the efficiency of local approximations and the improved quality of global approximations are combined to obtain an effective solution procedure.The method is based on results of a single exact analysis and can be used with a general finite element system. It is suitable for different types of structures, such as trusses, frames, grillages, etc. Calculations of derivatives is not required, and the errors involved in the approximations can readily be evaluated.Several numerical examples illustrate the effectiveness of the solution procedure. It is shown that excellent results can be achieved with small computational effort for very large changes in the cross-sections and in the topology of the structure.     

基于Micro-agent的自主机器人车辆

针对合作Agent的应用问题阐述了一种面向Agent的程序设计方法框架MAOP。提出了一种新的面向Micro—Agent的编程语言MAOPOL,描述了可执行Micro-Agent的生成过程,并在此基础上构建了一个自主机器人车辆。仿真实验结果表明系统中的自主机器人车辆能够协调处理较复杂的应用问题。     

Adaptive local thresholding by verification-based multithreshold probing with application to vessel detection in retinal images

In this paper, we propose a general framework of adaptive local thresholding based on a verification-based multithreshold probing scheme. Object hypotheses are generated by binarization using hypothetic thresholds and accepted/rejected by a verification procedure. The application-dependent verification procedure can be designed to fully utilize all relevant informations about the objects of interest. In this sense, our approach is regarded as knowledge-guided adaptive thresholding, in contrast to most algorithms known from the literature. We apply our general framework to detect vessels in retinal images. An experimental evaluation demonstrates superior performance over global thresholding and a vessel detection method recently reported in the literature. Due to its simplicity and general nature, our novel approach is expected to be applicable to a variety of other applications.     

An automatic microfluidic system that continuously performs the systematic evolution of ligands by exponential enrichment

The systematic evolution of ligands by exponential enrichment (SELEX) technique has been extensively used to screen molecule-specific aptamers from combinatorial libraries of synthetic nucleic acids. Aptamers are single-stranded DNA or RNA, which have a high affinity to a large variety of molecules ranging from small drugs or metabolites to cells. Therefore, they have a variety of promising applications such as for diagnostics and targeted therapeutics. In this study, a new microfluidic chip was developed to perform continuous screening of DNA-based aptamers in an automatic format. When compared with the existing manual procedure, the developed microfluidic chip has several advantages including a rapid and efficient screening process, automation, and less consumption of samples/reagents. Experimental data showed that an aptamer specific to alpha-fetoprotein was successfully screened from a random DNA pool. The entire screening process (five continuous, repetitive rounds) can be completed within 6?h, which is much faster than the traditional methods (more than 15?h). An automatic, rapid and efficient SELEX process was performed by this developed microfluidic chip, which may enable a generalized platform for the fast screening of DNA-based biomarkers in the future.     

Analysis of dynamics trajectories of DNA and DNA-drug complexes

A FORTRAN-77 program is described which was applied for analysis of optimized structures and computer-generated dynamics trajectories of DNA and DNA-drug complexes. The CORDAN program (coordinates analysis) also can be used for various manipulations of DNA-drug complexes, i.e. inversion of asymmetric sites or rebuilding the structure of the intercalator, among others. These procedures can find application in drug design. Analysis of dynamics trajectory of neocarzinostatin antibiotic (NCS) intercalated to the A-DNA form of 5'GGATGGGAG:5'CTCCCATCC is presented. The procedures described can be used for detailed analysis of dynamics structures of DNA and their complexes with intercalating drugs.     

Data structures in SL5

The procedural approach to data structures used in the SL5 programming language is described. The SL5 procedure mechanism forms the basis for this approach to data structures by treating procedures and their activation records (environments) as data objects and by decomposing the traditionally atomic operation of procedure invocation into more elementary components. The basic idea is that environments, since they are data objects, can also be used as data structures. The result is a single unified linguistic mechanism for constructing both procedures and data structures. Several examples are given.     

An efficient procedure for computing exact confidence limits for a standardized mortality ratio

An efficient computing procedure is described for obtaining exact confidence limits for the mean of a Poisson distribution. It is shown how this procedure can be used to obtain the exact confidence limits for a standardized mortality ratio, a parameter of great interest to epidemiologists. An example is presented illustrating the technique.     

A response surface based optimisation algorithm for the calculation of fuzzy envelope FRFs of models with uncertain properties

This paper describes a response surface based optimisation technique for the calculation of envelope frequency response functions (FRFs) of imprecisely defined structures using the interval and fuzzy finite element method.The authors developed a hybrid - global optimisation and interval arithmetic - procedure for interval and fuzzy envelope FRF calculation. This hybrid approach reduces the computational cost of the analysis compared to a full global optimisation approach and reduces the conservatism on the envelope FRF compared to a full interval arithmetic approach.Still, the optimisation step is the computationally most expensive part of the algorithm. To handle industrially sized applications, a very efficient optimisation procedure is imperative. The response surface based procedure described in this paper decreases the computational cost of a fuzzy envelope FRF calculation with a factor 50 or more compared to the commonly used two-level full factorial design of experiments, while giving a comparable accuracy.     

Automatic selection of control-points from shadow structures†

Abstract

The purpose of this paper is to describe a procedure for the automatic selection of control-points in remote-sensing images of high-relief terrains for alignment with a reference map. This problem has been found to be of strategic importance whenever remote sensing images have to be integrated in a Geographic Information System (GIS) and processed in real time. The procedure described here is based on the recognition of shadow structures in the satellite image and on their comparison with the computer-generated shadows obtained from the Digital Terrain Model (DTM) of the region. The procedure was developed for a Landsat TM image of the Aurina Valley (in the Pusteresi Alps) with the DTM obtained from an IGM (Istituto Geografico Militare) 1:25000 reference map, but with minor changes it can be extended to other remote-sensing images. Comparison of the shadow structures is performed by similarity evaluation of a simplified model of their shapes described by means of inertia ellipses. Each pair of shadow structures, recognized as similar and meeting a number of positional constraints, yields a pair of corresponding points whose coordinates provide input values for determining the parameters in the transformation of the input image into a planimetrically corrected one. The performance and robustness of the method and its boundary applicability are assessed. An example is given in which the automatically-determined control-points are directly inserted in a warping function, with reasonably good results.     

Shear flow distribution in multi-cell girders

A computer program is described for the shear flow analysis of multi-cell girders. The basic assumption of the theory used is that the loading pattern does not cause any distortion of a transverse section of the girder. The computer routine is based on a system of defining girder cross-sectional layouts which can be applied to a wide variety of beams with a minimum of data preparation and coding. The difficulties encountered in devising the routine and the solutions adopted are described in detail. The method is demonstrated on three different beam cross-sections taken from ship structures.     

可满足性问题的三维DNA图结构算法

论文提出用三维图结构解决DNA分子计算问题,给出了解决3-SAT问题的方法。在所提出的方法中,算法所要求的步骤与公式中变量的数目相等。     

Object-oriented query language access to relational databases: A semantic framework for query translation

This research investigates and approach to query processing in a multidatabase system that uses an objectoriented model to capture the semantics of other data models. The object-oriented model is used to construct a global schema, defining an integrated view of the different schemas in the environment. The model is also used as a self-describing model to build a meta-database for storing information about the global schema. A unique aspect of this work is that the object-oriented model is used to describe the different data models of the multidatabase environment, thereby extending the meta database with semantic information about the local schemas. With the global and local schemas all represented in an object-oriented form, structural mappings between the global schema and each local schema are then easily supported. An object algebra then provides a query language for expressing global queries, using the structural mappings to translate object algebra queries into SQL queries over local relational schema. The advantage of using an object algebra is that the object-oriented database can be viewed as a blackboard for temporary storage of local data and for establishing relationships between different databases. The object algebra can be used to directly retrieve temporarily-stored data from the object-oriented database or to transparently retrieve data from local sources using the translation process described in this paper.     

Runge–Kutta Residual Distribution Schemes

We are concerned with the solution of time-dependent non-linear hyperbolic partial differential equations. We investigate the combination of residual distribution methods with a consistent mass matrix (discretisation in space) and a Runge–Kutta-type time-stepping (discretisation in time). The introduced non-linear blending procedure allows us to retain the explicit character of the time-stepping procedure. The resulting methods are second order accurate provided that both spatial and temporal approximations are. The proposed approach results in a global linear system that has to be solved at each time-step. An efficient way of solving this system is also proposed. To test and validate this new framework, we perform extensive numerical experiments on a wide variety of classical problems. An extensive numerical comparison of our approach with other multi-stage residual distribution schemes is also given.     

Identification of a Wiener–Hammerstein system using an incremental nonlinear optimisation technique

A method for black-box identification of a Wiener–Hammerstein system is described and applied to a set of Benchmark data originally presented at the 15th IFAC Symposium on System Identification. An incremental nonlinear optimisation procedure is used, which is able to avoid local minima, thus enabling the solution to converge to the global minimum. The use of a dual-polynomial to describe the static nonlinearity allows the number of parameters needed to be significantly reduced compared with the case if a single polynomial is utilised; this also improves robustness against extrapolation errors. The overall approach requires a relatively small number of parameters.     

Random eigenvalue problems for large systems

The inherent uncertainties in geometry, material properties, etc. of engineering structures can be represented by stochastic models, where the parameters are described by probabilistic laws. Results from any analysis based on stochastic models inherit probabilistic information as well, which can be used e.g. for reliability analysis. Particularly in linear dynamics of structures the calculation and analysis of random eigenvalues and eigenvectors is crucial. A quite versatile, however computationally intensive way to analyze such systems is direct Monte Carlo simulation. In this paper procedures are shown, which allow a significant reduction of computational efforts of the simulation using a subspace iteration scheme with “optimally” selected start-vectors. As the subspace iteration procedure, although quite accurate, requires a factorization of the stiffness matrix, as an alternative, a procedure based on component mode synthesis is suggested.     

连通度问题的三维DNA结构进化算法

针对求连通度这一难解问题,提出了三维DNA图结构进化算法。并提出了一种由k-臂DNA分子构建的图结构。在所述方法中3、4臂DNA分子的顶点构造块被选择性地用来构建一些不同的图结构。然后通过凝胶电泳分离,图的连通度便可确定。并且通过引入进化算法的思想,避免了解空间的穷举。     

On-line structure selection for multivariable state-space models

An algorithm is described for the selection of model structure for identifying state-space models of ‘black box’ character. The algorithm receives as ‘input’ a given system in a given parametrization. It is then tested whether this parametrization is suitable (well conditioned) for identification purposes. If not, a better one is selected and the transformation of the system to the new representation is performed. This algorithm can be used as a block both in an iterative, off-line identification procedure, and for recursive, on-line identification. It can be called whenever there is some indication that the model structure is ill-conditioned. It is discussed how the model structure selection algorithm can be interfaced with an off-line identification procedure. A complete procedure is described and tested on real and simulated data.